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Viewing 241 to 270 of 17076
2016-04-05
Technical Paper
2016-01-1403
Jeff D. Colwell, Christopher D. Henry
Abstract Data from a full-scale vehicle burn test involving a cargo van illustrated how temperature distributions changed over time, the manner in which fire spread, and how patterns produced correlated to the origin of the fire. The fire was initiated on the driver’s side of the engine compartment and initially grew slowly with the high-temperature zone near the area of origin. Once the peak temperature reached about 540°C, the rate of flame spread increased such that over the next 4 minutes the fire spread across the entire engine compartment. In the next stage of the fire, which occurred shortly after full involvement of the engine compartment, the fire spread into the passenger compartment. A strong vertical temperature gradient developed from the ceiling to the floor and as the passenger compartment became fully involved, the passenger compartment temperatures both increased and became more uniform.
2016-04-05
Technical Paper
2016-01-1370
Vali Farahani, Salamah Maaita, Aditya Jayanthi
Abstract During the course of automobile Instrument Panel (IP) design development, the occupant head impact CAE simulation on IP are routinely performed to validate FMVSS201 requirements. Based on FMVSS201 requirements, the potential head impact zones on the IP are first identified. Then, the head impact zones are used to locate the various target points that must be impacted on IP. Once the critical target locations on IP are chosen, there are several computational steps that are required to calculate impact angles and head form (HF) center of rotation in reference to target points. Then, CAE engineer performs a repetitive process that involves positioning each individual HF with proper impact angle, assigning initial velocity to HF, and defining surface contacts within the finite element model (FEM). To simplify these lengthy manual steps, a commercially available software HyperMesh® CAE software tool is used to automate these steps.
2016-04-05
Journal Article
2016-01-1456
Rini Sherony, Renran Tian, Stanley Chien, Li Fu, Yaobin Chen, Hiroyuki Takahashi
Abstract Many vehicles are currently equipped with active safety systems that can detect vulnerable road users like pedestrians and bicyclists, to mitigate associated conflicts with vehicles. With the advancements in technologies and algorithms, detailed motions of these targets, especially the limb motions, are being considered for improving the efficiency and reliability of object detection. Thus, it becomes important to understand these limb motions to support the design and evaluation of many vehicular safety systems. However in current literature, there is no agreement being reached on whether or not and how often these limbs move, especially at the most critical moments for potential crashes. In this study, a total of 832 pedestrian walking or cyclist biking cases were randomly selected from one large-scale naturalistic driving database containing 480,000 video segments with a total size of 94TB, and then the 832 video clips were analyzed focusing on their limb motions.
2016-04-05
Technical Paper
2016-01-1454
Libo Dong, Stanley Chien, Jiang-Yu Zheng, Yaobin Chen, Rini Sherony, Hiroyuki Takahashi
Abstract Pedestrian Automatic Emergency Braking (PAEB) for helping avoiding/mitigating pedestrian crashes has been equipped on some passenger vehicles. Since approximately 70% pedestrian crashes occur in dark conditions, one of the important components in the PAEB evaluation is the development of standard testing at night. The test facility should include representative low-illuminance environment to enable the examination of the sensing and control functions of different PAEB systems. The goal of this research is to characterize and model light source distributions and variations in the low-illuminance environment and determine possible ways to reconstruct such an environment for PAEB evaluation. This paper describes a general method to collect light sources and illuminance information by processing large amount of potential collision locations at night from naturalistic driving video data.
2016-04-05
Technical Paper
2016-01-1453
I-Hsuan Lee, Bi-Cheng Luan
Abstract Autonomous emergency braking (AEB) systems is one of the functions of the Advanced Driver Assists System to avoid or mitigate vehicle frontal collisions. Most of the previous studies focus on two-car scenario where the host vehicle monitors the distances to the vehicles in front, and automatically applies emergency brake when a collision is imminent. The purpose of this paper is to develop an Advanced-AEB control system that mitigates collisions in a multi-car scenario by measuring the distances to the vehicles in front as well as those to the vehicles behind using the concept of impedance control. A simple gain-scheduling PI controller was designed for the host vehicle to track the reference inputs generated by the impedance control. The preliminary simulation results demonstrate that the proposed AEB is effective in mitigating the collisions in a 3-car following scenario.
2016-04-05
Technical Paper
2016-01-1451
Mingyang Chen, Xichan Zhu, Zhixiong Ma, Lin Li
Abstract In China there are many mixed driving roads which cause a lot of safety problems between vehicles and pedalcyclists. Research on driver behavior under risk scenarios with pedalcyclist is relatively few. In this paper driver brake parameters under naturalistic driving are studied and pedalcyclists include bicyclist, tricyclist, electric bicyclist and motorcyclist. Brake reaction time and maximum brake jerk are used to evaluate driver brake reaction speed. Average deceleration is used to evaluate the effect of driver brake operation. Maximum deceleration is used to evaluate driver braking ability. Driver behaviors collected in China are classified and risk scenarios with pedalcyclist are obtained. Driver brake parameters are extracted and statistical characteristics of driver brake parameters are obtained. Influence factors are analyzed with univariate ANOVA and regression analysis.
2016-04-05
Journal Article
2016-01-1449
Taylor Johnson, Rong Chen, Rini Sherony, Hampton C. Gabler
Abstract Lane departure warning (LDW) systems can detect an impending road departure and deliver an alert to allow the driver to steer back to the lane. LDW has great potential to reduce the number of road departure crashes, but the effectiveness is highly dependent upon driver acceptance. If the driver perceives there is little danger after receiving an alert, the driver may become annoyed and deactivate the system. Most current LDW systems rely heavily upon distance to lane boundary (DTLB) in the decision to deliver an alert. There is early evidence that in normal driving DTLB may be only one of a host of other cues which drivers use in lane keeping and in their perception of lane departure risk. A more effective threshold for LDW could potentially be delivered if there was a better understanding of this normal lane keeping behavior. The objective of this paper is to investigate the lane keeping behavior of drivers in normal driving.
2016-04-05
Technical Paper
2016-01-1446
Rini Sherony, Qiang Yi, Stanley Chien, Jason Brink, Mohammad Almutairi, Keyu Ruan, Wensen Niu, Lingxi Li, Yaobin Chen, Hiroyuki Takahashi
Abstract According to the U.S. National Highway Traffic Safety Administration, 743 pedal cyclists were killed and 48,000 were injured in motor vehicle crashes in 2013. As a novel active safety equipment to mitigate bicyclist crashes, bicyclist Pre-Collision Systems (PCSs) are being developed by many vehicle manufacturers. Therefore, developing equipment for evaluating bicyclist PCS is essential. This paper describes the development of a bicycle carrier for carrying the surrogate bicyclist in bicyclist PCS testing. An analysis on the United States national crash databases and videos from TASI 110 car naturalistic driving database was conducted to determine a set of most common crash scenarios, the motion speed and profile of bicycles. The bicycle carrier was designed to carry or pull the surrogate bicyclist for bicycle PCS evaluation. The carrier is a platform with a 4 wheel differential driving system.
2016-04-05
Technical Paper
2016-01-1447
Qiang Yi, Stanley Chien, Jason Brink, Wensen Niu, Lingxi Li, Yaobin Chen, Chi-Chen Chen, Rini Sherony, Hiroyuki Takahashi
Abstract As part of active safety systems for reducing bicyclist fatalities and injuries, Bicyclist Pre-Collision System (BPCS), also known as Bicyclist Autonomous Emergency Braking System, is being studied currently by several vehicles manufactures. This paper describes the development of a surrogate bicyclist which includes a surrogate bicycle and a surrogate bicycle rider to support the development and evaluation of BPCS. The surrogate bicycle is designed to represent the visual and radar characteristics of real bicyclists in the United States. The size of bicycle surrogate mimics the 26 inch adult bicycle, which is the most popular adult bicycle sold in the US. The radar cross section (RCS) of the surrogate bicycle is designed based on RCS measurement of the real adult sized bicycles.
2016-04-05
Technical Paper
2016-01-1474
Edward C. Fatzinger, Tyler L. Shaw, Jon B. Landerville
Abstract Six electronic needle-display speedometers from five different manufacturers were tested in order to determine the behavior of the gauges following a power interruption and impact. Subject motorcycles were accelerated to pre-determined speeds, at which point the speedometer wiring harness was disconnected. The observed results were that the dial indicator would move slightly up, down, or remain in place depending on the model of the speedometer. The observed change of indicated speed was within +/- 10 mph upon power loss. Additionally, the speedometers were subjected to impact testing to further analyze needle movement due to collision forces. Speedometers were attached to a linear drop rail apparatus instrumented with an accelerometer. A minimum acceleration due to impact which could cause needle movement was measured for each speedometer assembly.
2016-04-05
Technical Paper
2016-01-1471
Anthony Timpanaro, Charles Moody, Wesley Richardson, Bradley Reckamp, Orion Keifer
Abstract It is well known that older vehicles’ headlight assemblies degrade with exposure to the elements and can become cloudy or crazed. It is also known that the degradation decreases the amount of useful light projected forward, which can drastically reduce night time or down-road visibility. Testing has been performed to measure the available light projected by old degraded headlamp assemblies and new replacement assemblies, to quantify the decrease in emitted light caused by the degradation. The work has been extended to quantify the improvement in available light when the degraded lenses are treated with commercially available restoration products. Five different vehicle headlamp assemblies representing four different manufacturers were tested measuring the illumination at a given distance with a modified Extech® illuminance meter.
2016-04-05
Technical Paper
2016-01-1472
Dietmar Otte, Martin Urban, Heiko Johannsen
Abstract Estimating the potential benefit of advanced safety systems by simulation has become increasingly important during the last years. All over the world OEMs and suppliers carry out benefit estimations by simulations via computer models. Such simulations should, of course, be based on real world scenario such as the pre-crash phase of real world accidents. Several methodologies for building up accident scenarios have been developed in the past. This paper shows a new method for generating pre-crash scenarios directly from the reconstruction of the accident by using the software PC-Crash1. The new method was developed by the Medical University Hannover (MHH) and the Fraunhofer Institute for Transportation Dresden (Fraunhofer IVI). It is based on transferring all information (participant-, vehicle-, environment- and motion-data) from the reconstruction file into a scenario-database.
2016-04-05
Technical Paper
2016-01-1465
John Zolock, Carmine Senatore, Ryan Yee, Robert Larson, Brian Curry
Abstract As a result of the development of Event Data Recorders (EDR) and the recent FMVSS regulation 49 CFR 563, today’s automobiles provide a limited subset of electronic data measurements of a vehicle’s state before and during a crash. Prior to this data, the only information available about the vehicle movements before or during a collision had come from physical evidence (e.g. tire marks), witnesses, aftermarket camera systems on vehicles, and ground-based cameras that were monitoring vehicle traffic or used for security surveillance. Today’s vehicles equipped with Advanced Driver Assistance Systems (ADAS) have vehicle-based sensors that measure information about the environment around a vehicle including other vehicles, pedestrians, and fixed wayside objects.
2016-04-05
Technical Paper
2016-01-1463
Jeffrey Aaron Suway, Judson Welcher
Abstract It is extremely important to accurately depict photographs or video taken of a scene at night, when attempting to show how the subject scene appeared. It is widely understood that digital image sensors cannot capture the large dynamic range that can be seen by the human eye. Furthermore, todays commercially available printers, computer monitors, TV’s or other displays cannot reproduce the dynamic range that is captured by the digital cameras. Therefore, care must be taken when presenting a photograph or video while attempting to accurately depict a subject scene. However, there are many parameters that can be altered, while taking a photograph or video, to make a subject scene either too bright or too dark. Similarly, adjustments can be made to a printer or display to make the image appear either too bright or too dark. There have been several published papers and studies dealing with how to properly capture and calibrate photographs and video of a subject scene at night.
2016-04-05
Technical Paper
2016-01-1464
Jorge Martins, Ricardo Ribeiro, Pedro Neves, F. P. Brito
Abstract The main source for the estimation of stiffness coefficients to be used in accident reconstruction calculations is a very large database of crash-test related information from NHTSA. However, that database includes only car models sold in the USA. Unfortunately, there is no such information for European-only cars besides the raw video recordings of EuroNCAP crash tests. In the present work a methodology is proposed to estimate the stiffness coefficients of European-only models from video images of EuroNCAP crash tests. However, these images are intricate to assess, because the car front is crushed into a deformable barrier at 40% of the front width and usually the bonnet (hood) hides most of the crash damage. Therefore, the top images could not be used straightforward, so a procedure was envisaged to circumvent this difficulty and still allow to calculate stiffness coefficients for European-only cars.
2016-04-05
Technical Paper
2016-01-1424
Yi G. Glaser, Robert E. Llaneras, Daniel S. Glaser, Charles A. Green
Abstract Partially automated driving involves the relinquishment of longitudinal and/or latitudinal control to the vehicle. Partially automated systems, however, are fallible and require driver oversight to avoid all road hazards. Researchers have expressed concern that automation promotes extended eyes-off-road (EOR) behavior that may lead to a loss of situational awareness (SA), degrading a driver’s ability to detect hazards and make necessary overrides. A potential countermeasure to visual inattention is the orientation of the driver’s glances towards potential hazards via cuing. This method is based on the assumption that drivers are able to rapidly identify hazards once their attention is drawn to the area of interest regardless of preceding EOR duration. This work examined this assumption in a simulated automated driving context by projecting hazardous and nonhazardous road scenes to a participant while sitting in a stationary vehicle.
2016-04-05
Technical Paper
2016-01-1420
Shinichi Kojima, Shigeyoshi Hiratsuka, Nobuyuki Shiraki, Kazunori Higuchi, Toshihiko Tsukada, Keiichi Shimaoka, Kazuya Asaoka, Sho Masuda, Kazuhiko Nakashima
Abstract This study aims at the development of a projection pattern that is capable of shortening the time required by a driver to perceive a pedestrian at night when a vehicle’s high beams are utilized. Our approach is based on the spatio-temporal frequency characteristics of human vision. Visual contrast sensitivity is dependent on spatiotemporal frequency, and maximum contrast sensitivity frequency varies depending on environmental luminance. Conventionally, there are several applications that utilize the spatio-temporal frequency characteristics of human vision. For example, the National Television System Committee (NTSC) television format takes into consideration low-sensitivity visual characteristics. In contrast, our approach utilizes high-sensitivity visual characteristics based on the assumption that the higher contrast sensitivity of spatio-temporal frequencies will correlate more effectively with shorter perception times.
2016-04-05
Journal Article
2016-01-1414
Shigeyoshi Hiratsuka, Shinichi Kojima, Nobuyuki Shiraki, Kazunori Higuchi, Toshihiko Tsukada, Keiichi Shimaoka, Kazuya Asaoka, Sho Masuda, Kazuhiko Nakashima
Abstract We investigated a lighting method that supports pedestrian perception by vehicle drivers. This lighting method makes active use of visual characteristics such as the spatio-temporal frequency of contrast sensitivity. Using reasonable parameter values derived from preliminary experiments using a Campbell-Robson chart, we determined a suitable lighting pattern that improves the driver's pedestrian perception. In order to assess the influence of visual characteristics on a reaction-time-dependent task, such as pedestrian perception in nighttime, tests were performed in the target environment, the results of which validated the proposed method.
2016-04-05
Technical Paper
2016-01-1417
Toshinao Fukui, Kazuhiko Nakamoto, Hiroyuki Satake
Abstract The use of a head-up display (HUD) system has become popular recently, as it can provide feedback information at a position easily seen by the driver. However, the outline of the HUD bezel often reflects on the windshield of a HUD equipped vehicle. This phenomenon occurs when the sun is at a high position and reflects off the top of the instrument panel and the front view is dark. For this reason, it can occur when driving on asphalt paved roads, causing annoyance to the driver. Under fixed environmental conditions, the vehicle based factors that influence the annoyance caused by reflected boundary lines are the position of the reflection, line thickness, and the contrast of the reflected boundary line. These can be represented by the conspicuity of a striped pattern (contrast sensitivity function). In previous research in 1991, M. S. Banks et al. studied a contrast sensitivity function that included the factors stated above.
2016-04-05
Technical Paper
2016-01-1412
Takeshi Hamaguchi, Satoshi Inoue, Shigeyuki Kimura, Terumasa Endo
Abstract In driver-focused vehicle development, driver workload is generally evaluated subjectively, with physiological, psychological, and behavioral indexes used to quantify and substantiate the subjective rating. In contrast, a model of driver behavior expresses the driver’s behavioral characteristics which make it possible to estimate how the driver will incorporate information into vehicle operation. Therefore, it is presumed to be capable of estimating the internal state of a driver. Conventionally, a model of driver behavior related to pedal operation has been used for evaluating the driver’s habits and the acceptability of various types of support devices. However, it has not been used for estimating driver workload related to pedal operation. To examine driver workload, this study divided pedal operation magnitude into two components: a learning/judgment component and a correcting component for prediction errors. A method was devised of separating these two components.
2016-04-05
Journal Article
2016-01-1439
Nazan Aksan, Lauren Sager, Sarah Hacker, Robert Marini, Jeffrey Dawson, Steven Anderson, Matthew Rizzo
Abstract We examined the effectiveness of a heads-up Forward Collision Warning (FCW) system in 39 younger to middle aged drivers (25-50, mean = 35 years) and 37 older drivers (66-87, mean = 77 years). The warnings were implemented in a fixed based, immersive, 180 degree forward field of view simulator. The FCW included a visual advisory component consisting of a red horizontal bar which flashed in the center screen of the simulator that was triggered at time-to-collision (TTC) 4 seconds. The bar roughly overlapped the rear bumper of the lead vehicle, just below the driver’s line-of-sight. A sustained auditory tone (∼80 dB) was activated at TTC=2 to alert the driver to an imminent collision. Hence, the warning system differed from the industry standard in significant ways. 95% Confidence intervals for the safety gains ranged from -.03 to .19 seconds in terms of average correction time across several activations. Older and younger adults did not differ in terms of safety gains.
2016-04-05
Technical Paper
2016-01-1442
David Miller, Mishel Johns, Hillary Page Ive, Nikhil Gowda, David Sirkin, Srinath Sibi, Brian Mok, Sudipto Aich, Wendy Ju
Abstract Age and experience influence driver ability to cope with transitions between automated and manual driving, especially when drivers are engaged in media use. This study evaluated three age cohorts (young/new drivers, adults, and seniors) on their performance in transitions from automated driving to manual vehicle control in a laboratory driving simulator. Drivers were given three tasks to perform during the automated driving segments: to watch a movie on a tablet, to read a story on a tablet, or to supervise the car's driving. We did not find significant differences in people's driving performance following the different tasks. We also did not find significant differences in driving performance between the people in each age group who successfully completed the study; however, the rejection rate of the senior age group was over 30% because many of the people in this age group had difficulty hearing instructions, understanding tasks, or remembering what to do.
2016-04-05
Technical Paper
2016-01-1437
Giorgio Previati, Massimiliano Gobbi, Giampiero Mastinu
Abstract The paper is focused on both the subjective and the objective ride comfort evaluation of farm tractors. The experimental measurement of the relevant accelerations occurring at the tractor body, at the cabin and at the seat was performed on a number of different farm tractors. A subjective rating of the ride comfort level was performed by considering five different drivers. The comfort index was computed according with ISO 2631 and other standards. The acceleration of the seated subject was computed by means of a proper mechanical model of a farm tractor and derived at different positions on the subject body. It turned out that the acceleration of the lower torso was particularly relevant for establishing a matching between the subjective perception and the objective measurement and computation. A number of indices have been derived from the measured data which are able to correlate the subjective driver feeling with the measured accelerations.
2016-04-05
Technical Paper
2016-01-1487
Zhenhai Gao, Chuzhao Li, Hongyu Hu, Chaoyang Chen, Hui Zhao, Helen Yu
Abstract At the collision moment, a driver’s lower extremity will be in different foot position, which leads to the different posture of the lower extremity with various muscle activations. These will affect the driver’s injury during collision, so it is necessary to investigate further. A simulated collision scene was constructed, and 20 participants (10 male and 10 female) were recruited for the test in a driving simulator. The braking posture and muscle activation of eight major muscles of driver’s lower extremity (both legs) were measured. The muscle activations in different postures were then analyzed. At the collision moment, the right leg was possible to be on the brake (male, 40%; female, 45%), in the air (male, 27.5%; female, 37.5%) or even on the accelerator (male, 25%; female, 12.5%). The left leg was on the floor all along.
2016-04-05
Journal Article
2016-01-1486
Qi Zhang, Bronislaw Gepner, Jacek Toczyski, Jason Kerrigan
Abstract While over 30% of US occupant fatalities occur in rollover crashes, no dummy has been developed for such a condition. Currently, an efficient, cost-effective methodology is being implemented to develop a biofidelic rollover dummy. Instead of designing a rollover dummy from scratch, this methodology identifies a baseline dummy and modifies it to improve its response in a rollover crash. Using computational models of the baseline dummy, including both multibody (MB) and finite element (FE) models, the dummy’s structure is continually modified until its response is aligned (using BioRank/CORA metric) with biofidelity targets. A previous study (Part I) identified the THOR dummy as a suitable baseline dummy by comparing the kinematic responses of six existing dummies with PMHS response corridors through laboratory rollover testing.
2016-04-05
Technical Paper
2016-01-1489
Logan Miller, James Gaewsky, Ashley Weaver, Joel Stitzel, Nicholas White
Abstract Crash reconstructions using finite element (FE) vehicle and human body models (HBMs) allow researchers to investigate injury mechanisms, predict injury risk, and evaluate the effectiveness of injury mitigation systems, ultimately leading to a reduced risk of fatal and severe injury in motor vehicle crashes (MVCs). To predict injuries, regional-level injury metrics were implemented into the Total Human Model for Safety (THUMS) full body HBM. THUMS was virtually instrumented with cross-sectional planes to measure forces and moments in the femurs, upper and lower tibias, ankles, pelvis (pubic symphysis, ilium, ischium, sacrum, ischial tuberosity, and inferior and superior pubic ramus), and the cervical, thoracic, and lumbar vertebrae and intervertebral discs. To measure accelerations, virtual accelerometers were implemented in the head, thoracic vertebrae, sternum, ribs, and pelvis.
2016-04-05
Technical Paper
2016-01-1491
Eunjoo Hwang, Jason Hallman, Katelyn Klein, Jonathan Rupp, Matthew Reed, Jingwen Hu
Abstract Current finite element (FE) human body models (HBMs) generally only represent young and mid-size male occupants and do not account for body shape and composition variations among the population. Because it generally takes several years to build a whole-body HBM, a method to rapidly develop HBMs with a wide range of human attributes (size, age, obesity level, etc.) is critically needed. Therefore, the objective of this study was to evaluate the feasibility of using a mesh morphing method to rapidly generate skeleton and whole-body HBMs based on statistical geometry targets developed previously. THUMS V4.01 mid-size male model jointly developed by Toyota Motor Corporation and Toyota Central R&D Labs was used in this study as the baseline HBM to be morphed. Radial basis function (RBF) was used to morph the baseline model into the target geometries.
2016-04-05
Technical Paper
2016-01-1493
Jeremy Daily, James Johnson, Amila Perera
Abstract Recovery of snapshot data recorded by Caterpillar engine control modules (ECMs) using Caterpillar Electronic Technician (CatET) software requires a complete snapshot record that contains information gathered both before and after an event. However, if an event is set and a crash ensues, or a crash creates an event, then it is possible for the ECM to lose power and not complete the recording. As such, the data may not be recoverable with CatET maintenance software. An examination of the J1708 network traffic reveals the snapshot data does exist and is recoverable. A motivational case study of a crash test between a Caterpillar powered school bus and a parked transit bus is presented to establish the hypothesis. Subsequently, a digital forensic recovery algorithm is detailed as it is implemented in the Synercon Technologies Forensic Link Adapter (FLA).
2016-04-05
Technical Paper
2016-01-1492
Ming Shen, Haojie Mao, Binhui Jiang, Feng Zhu, Xin Jin, Liqiang Dong, Suk Jae Ham, Palani Palaniappan, Clifford Chou, King Yang
Abstract To help predict the injury responses of child pedestrians and occupants in traffic incidents, finite element (FE) modeling has become a common research tool. Until now, there was no whole-body FE model for 10-year-old (10 YO) children. This paper introduces the development of two 10 YO whole-body pediatric FE models (named CHARM-10) with a standing posture to represent a pedestrian and a seated posture to represent an occupant with sufficient anatomic details. The geometric data was obtained from medical images and the key dimensions were compared to literature data. Component-level sub-models were built and validated against experimental results of post mortem human subjects (PMHS). Most of these studies have been mostly published previously and briefly summarized in this paper. For the current study, focus was put on the late stage model development.
2016-04-05
Technical Paper
2016-01-1485
Noritoshi Atsumi, Yuko Nakahira, Masami Iwamoto, Satoko Hirabayashi, Eiichi Tanaka
Abstract A reduction in brain disorders owing to traumatic brain injury (TBI) caused by head impacts in traffic accidents is needed. However, the details of the injury mechanism still remain unclear. In past analyses, brain parenchyma of a head finite element (FE) model has generally been modeled using simple isotropic viscoelastic materials. For further understanding of TBI mechanism, in this study we developed a new constitutive model that describes most of the mechanical properties in brain parenchyma such as anisotropy, strain rate dependency, and the characteristic features of the unloading process. Validation of the model was performed against several material test data from the literature with a simple one-element model. The model was also introduced into the human head FE model of THUMS v4.02 and validated against post-mortem human subject (PMHS) test data about brain displacements and intracranial pressures during head impacts.
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